1. Field of the Invention
The present invention relates to a display technology field, and more particularly to a reflective sheet, and a backlight module and a display screen using the same.
2. Description of Related Art
Currently, using a liquid crystal display device as a display part in an electric equipment is widely applied in various electric products. A backlight module is an important component in the liquid crystal display device. The function of the backlight module is to provide a sufficient brightness and an evenly distributed light source. Therefore, a lighting effect of the backlight module will directly affect the visual effect of the liquid crystal display device so that people requires a better design of the backlight module.
As shown in FIG. 1, a conventional backlight module mainly includes a light guide plate 1, an LED light source 2, a flexible circuit board 3, an optical film group 4, a plastic frame 5, a reflective sheet 6 and an adhesive tape 7 for connecting above parts. Wherein, the flexible circuit board 3 and the LED light source 2 are fixed to the light guide plate 1 and the plastic frame 5 through the adhesive tape 7. The optical film group 4 is disposed above the light guide plate 1. In the above backlight module, multiple LEDs are disposed separately. With reference to FIG. 2 and FIG. 3, in order to receive the LED light source 2, an inner side of the plastic frame 5 adjacent to the LED light source 2 is provided with multiple protrusion structures 8, and each LED light source is disposed between two adjacent protrusion structures. Because the LED light sources are separated, when the LED light sources emit lights, the lights are leaked out at gaps between adjacent LED light sources such that the lights emitted from the LED light sources toward the light guide plate 1 will generate a bright region and a dark region which is known as a hotspot phenomenon. The hotspot phenomenon will seriously affect the optical quality of the backlight module. Besides, locations of the plastic frame corresponding to the dark regions of the lights will absorb lights reflected by the light guide plate so as to cause the loss of the lights and decrease the utilization efficiency of the lights.
A patent, CN 201220159480.2, discloses a backlight module without the hotspot phenomenon. The backlight module includes a light guide plate (LGP) and an LED bar located at a light incident side of the light guide plate. Between the light guide plate and the LED bar, a light atomization device is provided. Using the light atomization device, lights emitted from the LED bar are dispersed to be an entire and even light emitting source in order to eliminate the hotspot phenomenon.
A patent, CN 201210082715.7, discloses a backlight module and a liquid crystal display device, including a light guide plate, a light source and a backplane. Through disposing a cave extended toward external of the backlight module opposing to a light incident surface of the light guide plate at a side wall of the backplane, and placing the light source in the cave such that an inner distance of the light source and the plastic frame is increased. That is, “A” value is increased in order to effectively eliminate the dark region formed by the lights emitted from the light source.
A patent, CN 201210483485.5, discloses a backlight module including an LED light source, a light guide plate, a light guide bar disposed between the LED light source and the light guide plate and a microstructure on the light guide bar. Besides, the patent utilizes the microstructure to effectively improve the hotspot phenomenon.
Although the conventional art provides some methods to solve the hotspot phenomenon, some of the methods require using additional parts in the backlight module so that the product cost is increased, and some of the methods cannot achieve an expected result. Based on the above analysis, a more reasonable backlight module structure is required to use the light source effectively, decrease the risk of the hotspot phenomenon and simplify the design of the backlight module.